Intercooler fan on constantly - Help with wiring, pic included

[Mr2Owner]

The Intercooler fan is on constantly on my Rev3 turbo Mr2. From reading on this forum I believe it can be on constantly if the sensor is broken or unplugged.

The sensor was connected and I replaced it with a new one as it was only 20 quid but it still remains on constantly so these 2 suggestions can be ruled out.

Ive checked the wiring from the bit I can see and there is a tiny bit of exposed wire directly at the connector as circled in my picture, which I doubt is a problem. There are 2 wires to the switch a solid blue and a brown/blue. The brown/blue has 11v when I test it with my multimeter, the solid blue wire doesn't have a voltage reading, is it an earth? Is there a test I can do with the meter to check this other wire, i'm not sure how to test for an earth?

[mr2magic]

Test for continiuty (the beep sound) against a known ground

[Mr2Owner]

Test for continiuty (the beep sound) against a known ground

Cheers for the reply. I actually did try that beep test when I was at it. It didn't beep when I had a probe on an earth bolt and other probe on the wire. But I didn't know if that wire should have made a beep or not? Should it have if its an earth wire?

[MartinF]

Unplug that connector and perform a continuity test from that exposed piece of wire to the other side of the connector, the side which attaches to the sensor. I suspect it's open circuit.

If so you will need to find somebody with a spare loom and ask if they'll supply you that connector with a length of wire still and repair yours.

Regardless you need to come up with a way of insulating that wire as it doesn't look great and will slowly deteriorate and end up breaking at some point.

[Mr2Owner]

Unplug that connector and perform a continuity test from that exposed piece of wire to the other side of the connector, the side which attaches to the sensor. I suspect it's open circuit.

If so you will need to find somebody with a spare loom and ask if they'll supply you that connector with a length of wire still and repair yours.

Regardless you need to come up with a way of insulating that wire as it doesn't look great and will slowly deteriorate and end up breaking at some point.

I tried that test there this evening and I have continuity between the bare bit of wire and the contact point in the sensor. I also have continuity between that wire and a earth bolt on the engine. Does this mean that wire is ok?

I don't have continuity between the other wire and an earth bolt on the engine, but I think that's correct as it has 12volts when ignition on so its the live, should the live have continuity to a earth bolt?

Does anyone have any other ideas I could try?

[mr2magic]

Do this....

[Mr2Owner]

Do this....Image Replaced With URL For Quote http://mr2.ie/mr2/bgb/mk2/mechanical/ma ... 2_0001.jpg

Thanks for the diagram dude. I've a few questions in trying to follow that procedure that maybe you could help me with.

Regards the first step checking the Wiring harness connector, how do i check for voltage at the connector with it disconnected. It states to disconnect it, or do I back probe these wires?

Am I reading the below tests correct??
So pin 1 i've to check for continuity between pin 1 and the car chasis ground point?
Pin 2 I've to check for voltage, do i put the other probe of my multimeter on a chasis ground point?
Pin 3 - Do the same as Pin 2 test?
Pin 5-6, Do i check the resistance bewteen pin 5 and pin 6, by putting the probes of my multimeter on pins 5 and 6 at the same time?
Pin 7 - Do the same test as i described for pins 2 and 3?
Pin 9 Check for continuity by putting 1 probe on pin 9 and the other pin on the chasis ground?

Have I got this correct? Am I correct in saying i can do the continuity test with the harness connector disconnected but for the voltage tests I'll have to have the connector plugged in and back probe the wires?

[mr2magic]

Do as the bgb tells you . 1 to 3 all refer to the harness side plug. I see you're not really versed with regards to wiring. Think of it as a gardena garden hose. The battery is your tap, the water is your voltage and the attachment is your sensor. If you remove the attachment from the hose there is still water pressure (voltage) in the hose. The same goes for the connector.....there is still battery voltage and battery ground on the harness side.

Pin 1,2,3,7 and 9 require you to put one probe on the pin and the other against the chassis with pin1 doing the beep test and pin 2,3,7 and 9 set to 20v dc on your multimeter.

Pin 5 and 6 are resistance measurements and require each pin to have a probe and the multimeter set to 2k ohms.

[Mr2Owner]

Do as the bgb tells you . 1 to 3 all refer to the harness side plug. I see you're not really versed with regards to wiring. Think of it as a gardena garden hose. The battery is your tap, the water is your voltage and the attachment is your sensor. If you remove the attachment from the hose there is still water pressure (voltage) in the hose. The same goes for the connector.....there is still battery voltage and battery ground on the harness side.

Pin 1,2,3,7 and 9 require you to put one probe on the pin and the other against the chassis with pin1 doing the beep test and pin 2,3,7 and 9 set to 20v dc on your multimeter.

Pin 5 and 6 are resistance measurements and require each pin to have a probe and the multimeter set to 2k ohms.

Ok, that clears it up a good bit, I should be able to do them tests tomorrow. Do you know where abouts that connector I've to disconnect and test actually is on the car, wheres the fan Ecu? Cheers, ill post the results tomorrow

[mr2magic]

On a usdm car the fan ecu is in the boot behind the liner close to where the ecu is. Its a little black plastic box about the size of a packet of cigarettes. I imagine it is the same on ukdm cars.

[Mr2Owner]

Only got round to do these tests today, heres the results:

Pin1 gave continuity with the beep sound.
Pin2 = 1.56V
Pin3 = 11.69V
Pin7 = 11.70V
Pin9 = 11.12V

Pin5 + Pin6 resistance = 2.41 with meter set at 20k. If I used the 2k setting on the meter I couldnt get a steady reading.

So does it seem everything is ok except for the low voltage reading of 1.56 on Pin2? Should Pin2 be reading near 12V like the other voltage readings?

@Mr2magic - would you happen to have the other pages of the manual that the page you posted refers to in the next steps like how to check the ignition main relay Page Ch-18.

And Page CO-23 inspecting main fan relay?

Would the manual tell us what exactly Pin2 connects to at the other end of the wire?

I appreciate the help and diagrams so far

[cosmos]

Why am i thinking that the temp sensor does not like being re-wired in any way….

[Mr2Owner]

Why am i thinking that the temp sensor does not like being re-wired in any way….

What do you mean?

[cosmos]

Well its a sealed connection, resistance perhaps? remember recalling that its a no no re doing this connection as you need the temp sensor unit and wire complete back to its source.

[mr2magic]

I have the complete manual (its also online just google mr2 bgb electrical or mr2 bgb mechanical) bit it's for the usdm turbo so the wiring may be just a tad different.

Pin 2 goes from the fan ecu to the combination meter and lights up the bulb when somethings wrong by grounding the circuit. If you only have approx 2 V on that wire then you need to take a good look at the 7.5A gauge fuse and the wiring to/from pin 2 respectively.

The sensor is a simple ntc and has resistance values way over anything a rewiring would add to that.

[Mr2Owner]

I have the complete manual (its also online just google mr2 bgb electrical or mr2 bgb mechanical) bit it's for the usdm turbo so the wiring may be just a tad different.

Pin 2 goes from the fan ecu to the combination meter and lights up the bulb when somethings wrong by grounding the circuit. If you only have approx 2 V on that wire then you need to take a good look at the 7.5A gauge fuse and the wiring to/from pin 2 respectively.

The sensor is a simple ntc and has resistance values way over anything a rewiring would add to that.

Cheers for the info. I'll try and check the wiring for pin2, mightn't be very accessible though. What and where is the combination meter and what bulb does it light up, a dash warning light? Which 7.5A fuse is it exactly, just 1 of the fan fuses in the fuse box or is there another 1 I need to look at?

[Mr2Owner]

I have the complete manual (its also online just google mr2 bgb electrical or mr2 bgb mechanical) bit it's for the usdm turbo so the wiring may be just a tad different.

Pin 2 goes from the fan ecu to the combination meter and lights up the bulb when somethings wrong by grounding the circuit. If you only have approx 2 V on that wire then you need to take a good look at the 7.5A gauge fuse and the wiring to/from pin 2 respectively.

The sensor is a simple ntc and has resistance values way over anything a rewiring would add to that.

@Mr2Magic, appreciate your info on this so far. Can you help a little more perhaps. Do you know where the "combination meter" is, is it behind the dash? If there's a problem with this pin2 wire should the engine fan warning light not be lit up on my dash? There is no warning light lit up on my dash.

[mr2magic]

Sorry, was busy with work.

The combination meter is your gauge cluster

I would remove the gauge cluster and swap out the small light bulb for the fan warning light. You will probably then have 12v on pin 2. If not then check the 7.5a gauge fuse and whether it gets 12v aswell.

[Mr2Owner]

Sorry, was busy with work.

The combination meter is your gauge cluster

I would remove the gauge cluster and swap out the small light bulb for the fan warning light. You will probably then have 12v on pin 2. If not then check the 7.5a gauge fuse and whether it gets 12v aswell.

Hiya, was hoping you'd reply!! I'd be lost on this without your steps to follow ha.

I done some more of the tests you suggested. I checked the 7.5A fuse, its in visible good condition and i did the continuity beep test on it and it beeped. I also did the continuity beep test on the metal pins in the fuse slot itself and it passed the beep test too.

I then checked the fuse slot pins for 12V and I got 12V on 1 of the pins with the ignition on. I done this with the fuse removed obviously.

Does this all seem good so far?
I didn't check the gauge bulb yet, I was leaving this till last as does it mean I've to start removing the dash, does the cluster come out easily, or is this an involved procedure?

[mr2magic]

Sounds good so far.

Getting the cluster out is a bit more involved. You need to remove all the plastic surrounds to be able to get to the screws holding the cluster in place including the shifter and radio surrounds.